Software to Automatically Test PLC Programs

We are working on developing complex PLC programs for our customers. Now a days we are facing some challenges for testing these programs as the number of programs that we needs to be tested increased significantly. We test all our programs at present manually and now it is almost impossible to test when ever there is a PLC firmware release.

Can any one suggest any tool to automate test for our programs. We are using CodeSys 2.3 platform currently. I am aware that CoDeSys 3 is supporting integrated automated testing.